Liquid filling machines which fill containers in a line are called in-line liquid fillers. Such fillers are, by definition, intermittent motion devices. Typically, containers are conveyed into the filling machine as a group. Each group is held stationary while each container within the group is completely filled with the requisite total fill of liquid. The total fill is generally determined by the use of a separate positive displacement pump for each container to be filled. Alternately, the fill dose may be based upon timed flow from a gravity reservoir elevated above the filling valves, or by a timed flow from a pressurized reservoir. In nearly all cases, the entire fill is placed into the container at one stop and then the entire group of containers is conveyed out of the machine to be replaced by a new group of empty containers, as in the Pro/Fill 3000 automatic fillers manufactured by the Oden Corporation of Buffalo, N.Y.
In a few known cases, containers may be partially filled at several locations as they move through the machine, but in these cases, a separate filling apparatus, generally a pump, is used at each filling location within the machine (see U.S. Pat. Nos. 3,648,741 and 3,651,836).
In all cases, a separate mechanical and/or electronic adjustment is required to establish the correct fill for each container position.
The common use of a separate filling apparatus and control for each filling position within the filling machine requires a complete duplication of hardware at each position. This duplication includes pumps, feed lines, drives, fill dose controls and filling shut-off valves or nozzles.
With in-line filling machines of the type described, several methods are utilized to enhance machine performance and utility or increase container throughput speeds. It is common practice to lower the filling nozzles into the bottom of the container and raise them up out of the bottle as the level of the liquid product rises in the container. This cycle is a time consuming and error prone practice and requires apparatus which can be complex and costly. It is frequently necessary, however, in order to allow adequate or enhanced liquid flow rates into containers without associated foaming of the liquid or turbulence induced gas entrainment into the liquid as it enters the container, leading in either case to overflow of the container during the filling process from foaming or boilout.
Another means of increasing container throughput in an in-line filling machine is to add filling positions. This requires additional duplication of lines, hardware, pumps and controls for each additional container filling position and makes the machine more complex and costly. Moreover, as each additional filling position is added, total machine output increases at a decreasing rate per added station and eventually begins to decrease in total containers per minute of output. This is because the indexing or transfer time of containers into and out of the machine becomes an ever greater proportion of the machine's total cycle time as filling positions are added.
The addition of diving nozzles (bottom-up container filling apparatus) and additional filling stations has the further negative effect of complicating and lengthening the initial set-up times required to make a filling machine operable with a particular liquid and container, and of complicating and lengthening the changing of the machine over from one particular liquid and container to another.
Another means of increasing container throughput in in-line liquid filling machines of known types is to decrease the liquid filling time by using the largest diameter filling nozzles possible consistent with the size of the container opening or neck. The use of larger nozzles reduces fluid velocity per unit area as it enters the container, thus reducing splash out effects. An unwanted result of this method is the much greater tendency of the filling nozzles to drip product onto the containers or machine between filling periods.